An ultrasound transducer element 20 includes: a substrate 11； and a cell group 10Z including a plurality of cells 10 each of which includes a lower electrode 12 arranged on the substrate 11, a membrane 18 including an upper electrode 16 arranged facing the lower electrode 12 with a cavity 14H positioned therebetween, and a plurality of pillars 14 forming the cavity 14H by supporting the membrane 18, each cavity 14H mutually communicating with one another.
